The invention relates to a method and apparatus for controlling the air supply in an internal combustion engine comprising:
a resonant collecting receiver having two partial collecting volumes,
at least two long resonant pipes via which air is drawn in below a predetermined limiting value for the speed of the internal combustion engine and each of which opens into in each case one of the two partial collecting volumes of the resonant collecting receiver, and
a separating element movable between a closed position separating the partial collecting volumes from one another during engine speeds below a predetermined limiting speed and an open position connecting the partial collecting volumes during engine speeds below the predetermined limiting speed.
In an internal combustion engine known from "MTZ 51 (1990) 4, pages 142-146 (illustration 4)", provision is made for the air to be drawn in via two relatively long resonant intake pipes. These two resonant intake pipes are connected to a resonant collecting receiver which can be divided into two partial collecting volumes via a flap as required, one resonant intake pipe being connected to one partial collecting volume and the other resonant intake pipe being connected to the other partial collecting volume. Up to a predetermined limiting speed, this flap is closed, as a result of which, by exploiting resonant effects, it is possible to achieve an improved volumetric efficiency and thus an improvement in the torque characteristic in the lower and middle speed ranges. In the higher speed ranges, this flap is opened. Due to the relatively long resonant intake pipes, power losses are to be expected particularly in the higher speed range.
An object on which the invention is based is to provide a method and apparatus of the type described above with which a higher torque characteristic can be achieved not only in the low and middle speed range but also in the high speed range.
This object is achieved according to the invention by providing an arrangement wherein simultaneously with the opening of the separating element, a cross-section of a short intake pipe connecting an intake line to the resonant collecting receiver is opened and the two long resonant intake pipes are closed.
With the method and apparatus according to the invention, the air is drawn in via a very short intake pipe precisely from the instant at which the two partial collecting volumes in the resonant receiver are connected to one another, i.e., from the instant at which a resonance effect is no longer present. The frictional losses or flow losses during the intake of the fresh air are thus markedly reduced, resulting in an improved volumetric efficiency and accordingly a higher torque characteristic. The development according to certain preferred embodiments with simultaneous closing of the long resonance intake pipes with the opening of the separating element has the additional effect that air is drawn in exclusively via the short intake pipe, thus excluding mutual influencing of the flows passing into the resonant collecting receiver via the long resonant intake pipes and the flows passing into the resonant collecting receiver via the short intake pipe.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.